It is customary to place solar panels of solar systems on roofs of buildings that they serve. It is also desirable to design the sun receiving portions of a building in such a way that the solar collector panels function differently from season to season to most effectively serve the varying seasonal energy absorbing and/or insulating requirements of the building.
It is known that the winter sun rises at its zenith to a lower angle than during any other period of the year (30.degree. in the sun belt); yet it is during the winter season that Solar heating systems must produce the maximum heat possible for the capacity of the system.
It is also known that Solar panels are most efficient as collectors when the plane of their insolation surface is substantially within 10.degree. of being perpendicular to the line of the sun's rays.
It is apparent, therefore, the south facing back wall of a conventional house receives more winter insolation than the shallow pitch roof of a conventional house because the back wall of the house is more perpendicular to the line of the sun's rays than the roof.
For the designer of a Solar system, it becomes especially evident that collector panels on the south wall and south facing roof must be positioned with care, to make optimum use of winter sun and least use of excess summary solar radiation, while as much as possible accommodating the objectives of desirable house design, such as having back windows to permit outward view and inward light.